In the game you find the setting under Settings → Keyboard/Mouse → Mouse Sensitivity.
The quicker way is the console: sensitivity 1.5
Conversion
Call of Duty to CS2 Sensitivity
In short: Call of Duty sens times 0.3. 5 becomes 1.5. For your own value, just edit the sentence below.
How to set it in CS2
What changes when you go from Call of Duty to CS2
CS2 turns 3.33 times further per mouse count than Call of Duty. That is why the number gets smaller while your mouse distance stays the same.
CS2 shows 26.3° more field of view than Call of Duty by default (106.26° against 80°). The picture looks a little wider and movement on screen a little slower.
In CS2 you can enter up to 3 decimal places. Use all of them to keep the conversion exact.
Common questions
How do I convert Call of Duty sens to CS2?
Multiply your Call of Duty sens by 0.3. 5 in Call of Duty becomes 1.5 in CS2.
Where do I set the sens in CS2?
Settings → Keyboard/Mouse → Mouse Sensitivity. Or in the console: sensitivity 1.5.
Why does CS2 still feel a bit different?
Call of Duty: Slider from 60 to 120 (horizontal, default 80). CS2: 90° at 4:3, about 106° at 16:9. Match the field of view as closely as you can; then the converted sens feels most natural.
Does this also apply to scopes?
No. The values are for hipfire. Zoom and scope sensitivities are set separately in the game.
Should I change my DPI?
No. Keep your DPI and only change the sens in the game. That keeps your feel the same everywhere.